Handled thermoplastic sacks are well known and are finding increasing use in the grocery sack market. Far and away the most common type of thermoplastic handled grocery sack is one made from a gusseted tube sealed at the top and the bottom with a suitable bag mouth and handle cutout, which yields a double layer of film in the handled region. There are two problems associated with this type of bag. One problem is the fact that the gusset folds of the bag are of necessity trapped in the bottom seal of the bag. This prevents the gusset from extending fully as product is loaded into the bag, which results in a wasteful loss of volume. The other problem is that where there are transitions from four-layers to two-layers along the heat-seal line of the bottom of the bag and forces are brought to bear at these transition points, as the bag attempts to expand, tears develop on both sides of the bag at the transition points.
U.S. Pat. No. 4,562,925 discloses a thermoplastic bag structure comprising a front and rear bag wall, a bottom and an open mouth top portion, the open mouth portion being characterized by having two pairs of single film handle loops each of which are located at opposite ends of the open mouth portion, the handles of each pair being side-by-side and each handle is an integral single film loop extension of the front and rear bag walls. The bag structures can be unitized by providing a detachable tab at the bag mouth opening and unitizing the bag structures through this tab. The method of forming the bags involves providing an end sealed collapsed thermoplastic film tube and removing plastic to form a bag mouth opening and handles at one end thereof. The resulting bag is an ungusseted bag which can be unitized into a pack by providing a detachable, unitizing tab at the bag mouth opening.
U.S. Pat. No. 4,699,608 is directed to a thermoplastic bag structure having, in its lay-flat condition, a front and rear bag wall, a two-film heat seal bottom; the outer side margins of the full length of the bag being folded toward but spaced from each other. The top most edge of each fold is heat sealed through the four films thereof along line corresponding to the width of the folds. An open mouth top portion being characterized by having double film handle loops at opposite ends of the mouth, the double film loops being extensions of the folded regions of the bags and the corresponding regions of the front and rear walls. The bag structures can be unitized by providing a detachable tab at the bag mouth opening and unitizing the bag structures through this tab. The method of forming the bags involves providing an end sealed collapsed thermoplastic film tube, folding the sides of the tube toward but spaced from each other, heat sealing one end of the tube through four layers thereof and removing plastic from this end of the structure to form a bag mouth and handles at one end thereof. The resulting bag is an ungusseted bag which can be unitized into a pack by providing a detachable, unitizing tab at the bag mouth opening.
U.S. Pat. No. 4,790,437 teaches a method for forming a thermoplastic film handled bag comprising: forming a continuous collapsed thermoplastic tube having heat seal lines across the width of the tube at bag length intervals, longitudinally folding opposite sides of the heat sealed tube equally towards each other until they meet at a common center line, folding the structure once again in the same direction along the center line and removing eight film layers in one of the corner regions defined by a heat seal line and the spine of the common center line fold, the film removal yielding a bag mouth opening and single loop handles at near the opposite ends of the bag mouth opening. Interconnected bags can be formed into a roll pack or individually severed bags can be unitized into a bag pack.
Despite these advances in the art, large handled bags having a volume suitable for industrial or home use, which may be produced in an economical manner, are not known to exist.